1. Field of the Invention
The present invention is generally related to a heat exchanger for a marine propulsion system and, more particularly, to a closed cooling system for a marine engine in which the heat exchanger is contained at a location spaced apart from the engine and supported by the transom of a marine vessel.
2. Description of the Related Art
Many different types of engine cooling systems are known for use in conjunction with marine propulsion systems. Some of these systems use an open cooling circuit in which water is drawn directly from a body of water and conducted into thermal communication with heat producing portions of the engine. Other cooling systems use a closed cooling circuit in which a coolant, such as ethylene glycol, is recirculated through cooling conduits of an engine to continually remove heat from heat producing portions of the engine. The engine coolant is then passed through a heat exchanger where heat is removed from the coolant by conducting the coolant in thermal communication with a raw water cooling conduit that directs a flow of water, from a body of water, through the heat exchanger. That raw water, after passing through the heat exchanger and removing heat from the engine coolant, is then returned to the body of water. These types of systems are well known to those skilled in the art.
U.S. Pat. No. 3,650,310, which issued to Childress on Mar. 21, 1972, describes a combination boat trim tab and heat exchanger. The trim tab body is hollow and has an inlet and outlet connected to the hollow interior and is adapted to be connected to the boat engine cooling system with elongate fins secured to the bottom of the outside of the body and axially aligned with the longitudinal axis of the boat. The hollow interior of the body includes a serpentine passageway between the inlet and outlet thereby increasing the heat exchange area in contact with the engine cooling liquid.
U.S. Pat. No. 4,220,121, which issued to Maggiorana on Sep. 2, 1980, discloses a heat exchanger for a marine propulsion engine. The heat exchanger is provided for a pressurized, closed cooling system for a marine propulsion engine. The heat exchanger includes a closed spiral passageway means for fresh cooling water drawn from the lake or other body of water. An outer housing encloses the spiral passageway and includes baffle means for directing of a coolant in a spiral path over the cooling passageway means within the housing. The coolant is thereby cooled by the circulating cold fresh water.
U.S. Pat. No. 4,338,993, which issued to Fernstrum on Jul. 13, 1982, describes an underwater outboard marine heat exchanger. A first water header is connected to a second water header by laterally spaced multiple parallel composite tubes in which each consists of two or more component tubes of vertically elongated rectangular cross-section welded to one another along their horizontal narrower adjoining faces. The height of each component tube is a multiplicity of times the width thereof.
U.S. Pat. No. 5,746,270 which issued to Schroeder et al. on May 5, 1998, discloses a heat exchanger for a marine engine cooling system. The heat exchanger assembly is provided for a marine propulsion system having a closed loop cooling system. The heat exchanger body encloses a series of tubes carrying seawater which removes heat from the engine coolant. The heat exchanger includes an integrally connected top tank. A single venting orifice is provided into the top tank from the heat exchanger body.
U.S. Pat. No. 6,379,201, which issued to Biggs et al. on Apr. 30, 2002, discloses a marine engine cooling system with a check valve to facilitate draining. The system is provided with a valve in which a ball moves freely within a cavity formed within the valve. Pressurized water, from a sea pump, causes the ball to block fluid flow through the cavity and forces pumped water to flow through a preferred conduit which may include a heat exchanger. When the sea pump is inoperative, the ball moves downward within the cavity to unblock a drain passage and allow water to drain from the heat generating components of the marine engine.
U.S. Pat. No. 6,544,085, which issued to Menard et al. on Apr. 8, 2003, describes a watercraft having a closed coolant circulating system with a heat exchanger that constitutes an exterior surface of the hull. The watercraft comprises a hull and an engine. It also comprises a heat exchanger formed from heat conductive material and having a fluid path defined therein with an inlet port and an outlet port. The heat exchanger has a heat exchanging exterior surface and is mounted to the hull such that the heat exchanging exterior surface constitutes a portion of the exterior surface of the hull that is normally disposed below the surface of the body of water.
U.S. Pat. No. 6,748,906, which issued to White et al. on Jun. 15, 2004, discloses a heat exchanger assembly for a marine engine. The heat exchanger for a marine internal combustion engine is disposed between first and second sides of a V-shaped engine configuration. A plurality of tubes and related structure are disposed within a cavity formed as an integral part of an air intake manifold of the engine. A first cooling fluid, such as ethylene glycol, is circulated in thermal communication with outer surfaces of the plurality of tubes within the heat exchanger and a second cooling fluid, such as lake or seawater, is circulated through the internal passages of the plurality of tubes. A conduit is provided within an end portion of the heat exchanger to remove heat from a lubricant, such as oil, of the internal combustion engine.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.
It would be significantly beneficial if the heat exchanger, of a closed loop marine propulsion system, could be provided in which the heat exchanger is located at a convenient position within the structure of a marine vessel. It would also be significantly beneficial if the heat exchanger could be disposed within a space that is not required for other uses in typical sterndrive-type marine propulsion systems.